Infrared.

A couple of weeks ago I read something on taking infrared photos with point-and-shoot digital cameras. I took a few shots after cobbling-together a red filter and two polarizers as a makeshift infrared filter. The results, while sort of interesting, weren't really infrared as far as I could tell. (The photo was brightened considerably using the Levels setting in The GIMP.)

Yesterday, purely by chance, I found myself looking at a site on using subminiature cameras. Oddly, there was a piece on making your own infrared filter by using combined red and green filters. I put a couple of my glass filters together, but that didn't seem to block much visible light. Then I got out my Roscolux filter pack and cut a square from #27 Medium Red and a square from #90 Dark Yellow Green. These two combined were almost black. I taped the stacked filters to the front of my cheap digital camera and the results were surprisingly good: 1, 2, 3, 4, 5.

The dark circle in the center of each photo is the only real problem and I don't know how to remedy that because it always pops up when I use really dark filters with this camera.